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Ilya [14]
2 years ago
14

Write a summary about the cell theory

Biology
2 answers:
xxTIMURxx [149]2 years ago
5 0

Answer:

The Cell Theory states: All living organisms are composed of cells. They may be unicellular or multicellular. The cell is the basic unit of life. Cells arise from pre-existing cells. (They are not derived from spontaneous generation .)

Explanation:

julia-pushkina [17]2 years ago
4 0

Answer:

Over the next two centuries after the discoveries of Hooke and Leeuwenhoek, biologists found cells everywhere. Biologists in the early part of the 19th century suggested that all living things were made of cells, but the role of cells as the primary building block of life was not discovered until 1839 when two German scientists, Theodor Schwann, a zoologist, and Matthias Jakob Schleiden, a botanist, suggested that cells were the basic unit of structure and function of all living things. Later, in 1858, the German doctor Rudolf Virchow observed that cells divide to produce more cells. He proposed that all cells arise only from other cells. The collective observations of all three scientists form the Cell Theory, which states that:

all organisms are made up of one or more cells,

all the life functions of an organism occur within cells,

all cells come from preexisting cells.

Though no one point of the Cell Theory is more important than another, the theory clearly states that the functions necessary for life occur in the cell. Findings since the time of the original Cell Theory have enabled scientists to "modernize" the theory, including points related to biochemistry and molecular biology. The modern version of the Cell Theory includes:

all known living things are made up of one or more cells,

all living cells arise from pre-existing cells by division,

the cell is the fundamental unit of structure and function in all living organisms,

the activity of an organism depends on the total activity of independent cells,

energy flow (metabolism and biochemistry) occurs within cells,

cells contain hereditary information (DNA) which is passed from cell to cell during cell division,

all cells are basically the same in chemical composition in organisms of similar species.

The Cell Theory is one of the main principles of biology. The points of the theory have been found to be true for all life. As with any scientific theory, the Cell Theory is based on observations that over many years upheld the basic conclusions of Schwann’s 1839 paper. However, one of Schwann’s original conclusions stated that cells formed in a similar way to crystals. This observation, which refers to spontaneous generation of life, was discounted when Virchow proposed that all cells arise only from other cells. The Cell Theory has withstood intense examination of cells by modern powerful microscopes and other instruments. Scientists continue to use new techniques and equipment to look into cells to discover additional explanations for how they work.

Explanation:

Hope I helped!

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How is a brain injury classified?
faltersainse [42]

Answer:

As an injury of the central nervous system.

Explanation:

Peripheral nervous system is the nervous system outside the brain and spinal cord. The central nervous system consists of the brain and spinal cord. The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions, such as the heart rate, digestion, respiratory rate, and more. The somatic nervous system is the part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles. Therefore, central nervous system is your answer!

Hope this helps :3

6 0
3 years ago
Read 2 more answers
_______________, harmful or helpful, is considered to be the source for new alleles and a main contributor to the diversity of l
ololo11 [35]

The right answer is A mutation.

Alteration of the genetic material (DNA or RNA) of a cell or virus that causes a change in certain traits due to the inheritance of this genetic material from generation to generation.

Abnormal modification of the DNA of a gene, either spontaneously during cell division, or under the influence of external agents called mutagens. This gene is modified to be transmitted to the daughter cells. Some mutations have no effect on the cell. Others are the first step in a long process of cancerization.

Rare are the mutations that are beneficial.

7 0
3 years ago
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Pregnancy, which is characteristically associated with changes in hormone levels in the body is a process tightly regulated by:
Blababa [14]

Answer:

Pregnancy, which is characteristically associated with changes in hormone levels in the body is a process tightly regulated by the hormon Human Chorionic Gonadotropin

Explanation:

The so-called pregnancy hormone is the Human Chorionic Gonadotropin (HCG). It only occurs during the gestation period and is responsible for regulating the entire process. Segregated by the placenta, it can be found in urine and blood.

The presence of the hormone in the urine allows to confirm the pregnancy with the test.   As in pregnancy, the placenta begins to form, the cells that make it up begin to stimulate the production of HCG, which causes the hormone levels to increase very rapidly in the first trimester of pregnancy

4 0
3 years ago
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Please help will mark brainliest!
Bumek [7]

Answer:

You can predict geno/pheno types using a Punnet square.

Explanation:

Some traits appear more often because they are dominant. Dominant traits win out over recessive genes.

6 0
3 years ago
How is it posibal to have ionic and covalent bonds
Brums [2.3K]

An atom  will usually form either an ionic bond or covalent bond with another atom but not both.

Ionic bonds are the kind of bonds that result when one atom transfers or gives up electrons and another atom receives them and adds them to its own energy shells.

An example is sodium metal and chlorine gas. Sodium gives up two of its electrons and Chlorine receives them and the two elements form an ionic bond to create sodium chloride, a new compound.

Covalent bonds are the kind of bonds formed when two atoms decide to share electrons. No atom gives up any electrons and neither does the other atom receive any. An example is water. An oxygen atom shares two of its electrons with two hydrogen atoms to form  a molecule of water (H2O).

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